1. Field Of The Invention
The present invention relates generally to a method of rehabilitating a pipe conduit which is in a damaged or deteriorated state, and more particularly to a method of lining a deteriorated conduit with a high strength corrosion resistant liner.
2. Description Of The Related Art
Various methods of rehabilitating a pipe conduit, which is buried underground, are known in the art. Generally speaking, such methods include the use of a liner having a diameter which is substantially the same as the inner diameter of the pipe conduit to be rehabilitated. The liner frequently includes an impermeable layer and an adjacent resin absorbing layer. This resin-absorbing layer impregnated with a liquid resin prior to the introduction into the pipe conduit. After being properly positioned in the pipe conduit, the liner is expanded and pressed against the inner surface of the pipe conduit by fluid pressure. While the liner is pressed against the inner surface of the pipe conduit, the resin is cured to form a rigid cured-in-place liner.
One known method of lining a pipe, disclosed in U.S. Pat. No. 4,770,562, uses a lining hose having an outer impermeable layer surrounding and adjacent to an inner resin-absorbent layer. The resin-absorbent layer is saturated with an excess volume of resin. The outer impermeable layer is then perforated to form a plurality of flow-through openings for the resin. The lining hose is subsequently introduced into the pipe conduit in a collapsed state, and the lining hose is shaped to conformingly line the pipe conduit. The shaping of the lining hose is accomplished by inverting an auxiliary hose, also known as a calibration hose, inside the lining hose. The inversion of the calibration hose inside the lining hose will force the excess amount of resin through the flow-through openings and into contact with the inner surface of the pipe conduit. The excess resin will also fill existing cracks and fissures in the conduit. A variation of the liner includes a thin layer of resin-absorbent material outwardly adjacent to the impermeable surface. This thin layer of resin-absorbent material facilitates the spreading of the excess resin once the impermeable layer has been perforated and the shaping of the lining hose process has begun.
Still another known method of rehabilitating a pipe, disclosed in U.S. Pat. No. 4,714,095, utilizes a lining hose having an impermeable outer layer surrounding a resin-absorbent inner layer, which is placed into a pipe conduit. The resin-absorbent layer of the lining hose is permeated with a resin. The lining hose is shaped to conformingly line the pipe conduit by inverting a calibrating hose into the lining hose and pressing the calibrating hose against the lining hose until the lining hose expanded against the pipe conduit. A surface region of a calibrating hose which is to contact the inner layer of the lining hose is provided with a layer containing a second resin. Inherent in the shaping is the purported mixture and/or reaction between the first and second resins along their adjoining surface. This mixture and/or reaction is said to initiate curing and cause at least one of the resins to commence hardening. A shortcoming of that method is that the reaction and/or mixture of the resins occurs only along the area of contact between the inner surface of the lining hose and the outer surface of the calibration hose. As a result, only the resin along the area of contract cures, leaving an inferior liner in place.
A discussed below, the present invention provides an inexpensive, easy to use method of providing corrosion protection, while at the same time providing the strength characteristics necessary for pipe rehabilitation.